Pedunculoside regulates tumor immune microenvironment and malignant characteristics of bladder cancer by TRAF6 mediated M2 macrophage polarization

Background: Pedunculoside (PE) is conductive to regulate tumor immune microenvironment and inhibits tumor growth and metastasis. However, the influence of PE in bladder Cancer is still indistinct. The research elucidates the effects of PE on the malignant characteristics of bladder Cancer by regulating TRAF6-mediated M2 macrophage polarization.

Material and methods: THP-1 cells were converted into M0 macrophages after PMA treatment, and then induced M2 polarization by IL4/IL13. The effect of PE on cell viability and invasion were examined by CCK-8, Transwell and western blot assays in M2 macrophage co-cultured bladder Cancer cells. The silence vectors and the overexpressed vectros of TRAF6 were transfected into M2 macrophage co-cultured bladder Cancer cells to investigate the regulatory mechanism of TRAF6 in PE affected bladder Cancer cells malignant phenotype. After establishment of subcutaneous tumor model, the function of PE in bladder Cancer cell growth in vivo were explored.

Results: M2 polarization was successfully induced by IL4/IL13, but inhibited by PE treatment. Moreover, bladder Cancer cell viability and invasion were significantly suppressed by PE in co-cultured M2 macrophages and J82/T24 cells. Additionally, PE treatment restrained TRAF6/NF-κB pathway, TRAF6 overexpression obviously reversed the inhibitory effects of PE on cell viability and invasion in co-cultured M2 macrophages and T24 cells. Furthermore, PE restrained bladder Cancer cells growth and reduced the protein levels of Ki-67, Vimentin and CD206 via regulating TRAF6/NF-κB pathway in vivo.

Conclusions: PE exhibited the inhibitory effects on M2 macrophage-induced bladder Cancer cells malignant characteristics by regulating TRAF6/NF-κB pathway.

Bladder cancer; Cell invasion; Cell viability; M2 macrophage; Pedunculoside; TRAF6/NF-κB.